Light emitting device and fabricating method thereof

ABSTRACT

A light emitting device includes: a substrate; a first electrode on the substrate; a metal member on the first electrode and having an cavity; a first insulating layer on the metal member and exposing the cavity therethrough; a bar-type LED having a first end portion and a second end portion; and a second electrode on the first insulating layer. The first end portion of the bar-type LED is in the cavity and electrically connected to the first electrode, and the second end portion of the bar-type LED protrudes outside of the cavity and is electrically connected to the second electrode.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean patentapplication 10-2018-0015888, filed on Feb. 8, 2018 in the KoreanIntellectual Property Office (KIPO), the entire disclosure of which isincorporated herein by reference.

BACKGROUND 1. Field

Aspects of the present disclosure relate to a light emitting device anda fabricating method thereof.

2. Related Art

Light emitting diodes (hereinafter abbreviated as LEDs) exhibitrelatively satisfactory durability even in poor environmental conditionsand have excellent performance in terms of lifespan and luminance.Recently, studies for applying LEDs to various light emitting deviceshave been actively conducted.

A technique for fabricating a bar-type LED on a micro or nano scale(e.g., a micro bar-type LED) by using an inorganic crystal structure,such as a structure in which a nitride-based semiconductor is grown, hasbeen studied. For example, the bar-type LED may be fabricated in a sizesmall enough to constitute a pixel of a self-luminescent display paneland the like.

SUMMARY

Embodiments of the present disclosure provide a light emitting devicethat includes a bar-type LED and has uniform or substantially uniformluminance characteristics and a fabricating method of the light emittingdevice.

According to an embodiment of the present disclosure, a light emittingdevice includes: a substrate; a first electrode on the substrate; ametal member on the first electrode and having an cavity; a firstinsulating layer on the metal member and exposing the cavitytherethrough; a bar-type LED having a first end portion and a second endportion; and a second electrode on the first insulating layer. The firstend portion of the bar-type LED is in the cavity and electricallyconnected to the first electrode, and the second end portion of thebar-type LED protrudes outside of the cavity and is electricallyconnected to the second electrode.

A width of an inside portion of the cavity may be larger than a width ofan entrance to the cavity.

A thickness of the metal member may be less than a length of thebar-type LED.

The cavity in the metal member may expose the first electrode.

The light emitting device may further include a plurality of bar-typeLEDs in the cavity.

The first insulating layer may have an inclined surface inclined withrespect to the cavity, and the bar-type LED may lean obliquely onto theinclined surface of the first insulating layer.

One pixel region may include a plurality of bar-type LEDs, and thebar-type LEDs in the one pixel region may be inclined in the samedirection.

One pixel region may include a plurality of bar-type LEDs, and thebar-type LEDs in the one pixel region may be inclined in directionsdifferent from each other.

The light emitting device may further include a connecting memberbetween the first end portion of the bar-type LED in the cavity and thefirst electrode.

The light emitting device may further include a second insulating layerbetween the first insulating layer and the second electrode. The secondinsulating layer may have a contact opening at where the second endportion of the bar-type LED and the second electrode are electricallyconnected to each other.

The light emitting device may further include alignment lines at bothsides of the first electrode.

According to another embodiment of the present disclosure, a method offabricating a light emitting device includes: forming a first electrodeon a substrate; forming a metal member on the first electrode; forming afirst insulating layer over the metal member, removing a portion of thefirst insulating layer to expose the metal member; forming an cavity inthe metal member; arranging a bar-type LED such that a first end portionof the bar-type LED is in the cavity and electrically connected to thefirst electrode; and forming a second electrode on the first insulatinglayer, the second electrode being electrically connected to a second endportion of the bar-type LED.

The cavity in the metal member may have a shape in which a width of itsinside portion is greater than a width of its entrance.

The cavity may be formed by isotropic etching.

A thickness of the metal member may be less than a length of thebar-type LED.

The first insulating layer may have an inclined surface inclined withrespect to the cavity, and the bar-type LED may lean obliquely onto theinclined surface of the first insulating layer.

The arranging of the bar-type LED may include: providing an LED solutioncomprising a plurality of bar-type LEDs on the first insulating layer;and after the providing the LED solution, cleaning the substrate in onedirection.

The method may further include forming a connecting member between thefirst end portion of the bar-type LED that is in the cavity and thefirst electrode.

The forming of the connecting member may include: forming a connectingmember layer on the first insulating layer and in the cavity; andetching the connecting member layer such that a portion of theconnecting member layer remains in the cavity.

The method may further include forming a second insulating layer havinga contact opening on the first insulating layer. The second end portionof the bar-type LED and the second electrode may be electricallyconnected to each other at the contact opening.

BRIEF DESCRIPTION OF THE DRAWINGS

Example embodiments of the present disclosure will now be described morefully hereinafter with reference to the accompanying drawings; however,the present disclosure may be embodied in different forms and should notbe construed as limited to the example embodiments set forth herein.Rather, these embodiments are provided so that this disclosure will bethorough and complete and will fully convey the scope of the presentdisclosure to those skilled in the art.

In the figures, dimensions may be exaggerated for clarity ofillustration. Like reference numerals refer to like elements throughout.

FIG. 1 is a perspective view illustrating a bar-type LED according to anembodiment of the present disclosure.

FIG. 2 is a structural diagram illustrating a light emitting deviceaccording to an embodiment of the present disclosure.

FIGS. 3A-3E are circuit diagrams illustrating a unit region of the lightemitting device in a passive light emitting display panel according toembodiments of the present disclosure.

FIGS. 4A-4C are circuit diagrams illustrating a unit region of the lightemitting device in an active light emitting display panel according toembodiments of the present disclosure.

FIG. 5A is a plan view illustrating an individual pixel region of thelight emitting device according to an embodiment of the presentdisclosure.

FIG. 5B is a sectional view taken along the line I-I′ of FIG. 5A.

FIGS. 6 and 7 are plan views illustrating pixel regions of lightemitting devices according to other embodiments of the presentdisclosure.

FIGS. 8A-8K are sectional views sequentially illustrating a fabricatingmethod of the light emitting device according to an embodiment of thepresent disclosure.

DETAILED DESCRIPTION

The present disclosure may include various changes and different shapes;therefore, only example embodiments are described herein. However, theseexample embodiments do not limit the present disclosure and cover allchanges and equivalent materials and replacements within the scope ofthe present disclosure.

It will be understood that, although the terms “first”, “second”, etc.may be used herein to describe various elements, these elements shouldnot be limited by these terms. These terms are only used to distinguishone element from another element. Thus, a “first” element discussedbelow could also be termed a “second” element without departing from thepresent disclosure. As used herein, the singular forms are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

It will be further understood that the terms “comprises,” comprising,”“includes,” “including”, and/or “having,” and variations thereof, whenused in this specification, specify the presence of stated features,integers, steps, operations, elements, and/or components but do notpreclude the presence and/or addition of one or more other features,integers, steps, operations, elements, components, and/or groupsthereof. Further, an expression that an element, such as a layer,region, substrate or plate, is placed “on” or “above” another elementindicates not only a case where the element is placed “directly on” or“just above” the other element but also a case where a further elementis interposed between the element and the other element. An expressionthat an element, such as a layer, region, substrate or plate, is placed“beneath” or “below” another element indicates not only a case where theelement is placed “directly beneath” or “just below” the other elementbut also a case where a further element is interposed between theelement and the other element.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to,” or “coupled to” another element or layer, itmay be directly on, connected, or coupled to the other element or layeror one or more intervening elements or layers may also be present. Whenan element or layer is referred to as being “directly on,” “directlyconnected to,” or “directly coupled to” another element or layer, thereare no intervening elements or layers present. For example, when a firstelement is described as being “coupled” or “connected” to a secondelement, the first element may be directly coupled or connected to thesecond element or the first element may be indirectly coupled orconnected to the second element via one or more intervening elements.Hereinafter, exemplary embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings.

As used herein, the term “and/or” includes any and all combinations ofone or more of the associated listed items. Further, the use of “may”when describing embodiments of the present invention relates to “one ormore embodiments of the present invention.” Expressions, such as “atleast one of,” when preceding a list of elements, modify the entire listof elements and do not modify the individual elements of the list. Also,the term “exemplary” is intended to refer to an example or illustration.As used herein, the terms “use,” “using,” and “used” may be consideredsynonymous with the terms “utilize,” “utilizing,” and “utilized,”respectively.

According to an embodiment of the present disclosure, a light emittingdevice including a bar-type LED LD is provided. A bar-type LED LD willfirst be described, and a light emitting device including the bar-typeLED LD will then be described.

FIG. 1 is a perspective view illustrating a bar-type LED LD according toan embodiment of the present disclosure. A cylindrical bar-type LED LDis illustrated in FIG. 1, but the present disclosure is not limitedthereto.

Referring to FIG. 1, the bar-type LED LD according to an embodiment ofthe present disclosure includes first and second conductivesemiconductor layers 11 and 13 and an active layer 12 interposed betweenthe first and second conductive semiconductor layers 11 and 13. Forexample, the bar-type LED LD may have a stacked structure in which thefirst conductive semiconductor layer 11, the active layer 12, and thesecond conductive semiconductor layer 13 are sequentially stacked. Insome embodiments, the bar-type LED LD may further include an insulatingfilm 14. The bar-type LED LD may further include a first electrode and asecond electrode.

In an embodiment of the present disclosure, the bar-type LED LD has abar shape extending in one direction. When it is assumed that theextending direction of the bar-type LED LD is a length direction, thebar-type LED LD has a first end portion and a second end portion alongthe length direction. In an embodiment of the present disclosure, one ofthe first and second conductive semiconductor layers 11 and 13 isdisposed at the first end portion, and the other of the first and secondconductive semiconductor layers 11 and 13 is disposed at the second endportion.

In some embodiments, the bar-type LED LD may have a cylindrical shape asshown in FIG. 1, but the shape of the bar-type LED LD is not limitedthereto. Here, the term “bar-type” includes a rod-like shape or bar-likeshape, which is long in its length direction (e.g., has an aspect ratiogreater than about 1), such as a cylindrical column or a polygonalcolumn. For example, the bar-type LED LD may have a length that isgreater than its diameter.

The bar-type LED LD may be fabricated small enough to have a diameterand/or a length measured on a micro or nano scale. However, the size ofthe bar-type LED LD is not limited thereto. For example, the size of thebar-type LED LD may be modified to correspond to conditions of a lightemitting device to which the bar-type LED LD is to be applied.

The first conductive semiconductor layer 11 may include, for example, ann-type semiconductor layer. For example, the first conductivesemiconductor layer 11 may include at least one semiconductor materialfrom among indium aluminum gallium nitride (InAlGaN), gallium nitride(GaN), aluminum gallium nitride (AlGaN), indium gallium nitride (InGaN),aluminum nitride (AlN), and indium nitride (InN) and may include asemiconductor layer doped with a first conductive dopant, such assilicon (Si), germanium (Ge), or tin (Sn). The first conductivesemiconductor layer 11 is not limited thereto, however, and the firstconductive semiconductor layer 11 may include various suitablematerials.

The active layer 12 is formed on the first conductive semiconductorlayer 11 and may have a single or multiple quantum well structure. Insome embodiments, a clad layer doped with a conductive dopant may beformed on the top and/or the bottom of (e.g., on opposite ends of) theactive layer 12. For example, the clad layer may be implemented as anAlGaN layer or an InAlGaN layer. In addition, the active layer 12 mayinclude (or may be made of) a material, such as AlGaN or indium galliumaluminum nitride (InGaAlN). When an electric field having a thresholdvoltage or greater (e.g., a predetermined voltage or greater) is appliedto both ends of the bar-type LED, electron-hole pairs are combined inthe active layer 12 such that the bar-type LED emits light.

The second conductive semiconductor layer 13 is formed on the activelayer 12 and may include a semiconductor layer of a type different fromthat of the first conductive semiconductor layer 11. As an example, thesecond conductive semiconductor layer 13 may include a p-typesemiconductor layer. For example, the second conductive semiconductorlayer 13 may include at least one semiconductor material from amongInGaAlN, GaN, AlGaN, InGaN, AlN, and indium nitride (InN), and mayinclude a semiconductor layer doped with a second conductive dopant,such as magnesium (Mg). The second conductive semiconductor layer 13 isnot limited thereto, however, and the second conductive semiconductorlayer 13 may include various suitable materials.

In some embodiments, the bar-type LED LD may further include theinsulating film 14, but the present disclosure is not limited thereto.In some embodiments, the insulating film 14 may be omitted.

In some embodiments, the insulating film 14 may be provided to cover atleast one region of the first conductive semiconductor layer 11, theactive layer 12, and the second conductive semiconductor layer 13. Forexample, the insulating film 14 may be provided at a portion other thanthe end portions of the bar-type LED LD so that the end portions of thebar-type LED LD are exposed. Also, in some embodiments, the insulatingfilm 14 may expose at least one region of the side surface of the firstconductive semiconductor layer 11 and/or the second conductivesemiconductor layer 13.

The insulating film 14 may be formed to surround at least a portion ofouter peripheral surfaces (e.g., outer circumferential surfaces) of thefirst conductive semiconductor layer 11, the active layer 12, and/or thesecond conductive semiconductor layer 13. As an example, the insulatingfilm 14 may be formed to surround at least the outer peripheral surfaceof the active layer 12. In some embodiments, the insulating film 14 maybe formed of a transparent insulating material. For example, theinsulating film 14 may include at least one insulating material selectedfrom the group consisting of silicon oxide (e.g., SiO₂), silicon nitride(e.g., Si₃N₄), aluminum oxide (e.g., Al₂O₃), and titanium oxide (e.g.,TiO₂). However, the present disclosure is not limited thereto andvarious suitable materials having insulating properties may be used.

The above-described bar-type LED LD may be used as a light emittingsource for various light emitting devices. As an example, the bar-typeLED LD may be used as a light emitting source for lighting devices orself-luminescent display panels.

FIG. 2 is a structural diagram illustrating a light emitting deviceaccording to an embodiment of the present disclosure. In FIG. 2, a lightemitting display device is illustrated as an example of a light emittingdevice using bar-type LEDs LD, but the light emitting device accordingto the present disclosure is not limited to the light emitting displaydevice illustrated in FIG. 2. As an example, the light emitting deviceaccording to the present disclosure may be another type of lightemitting device, such as a lighting device.

Referring to FIG. 2, the light emitting device according to anembodiment of the present disclosure includes a timing controller 110, ascan driver 120, a data driver 130, and a light emitting unit 140. Whenthe light emitting device is a light emitting display device, as in theillustrated embodiment, the light emitting unit 140 may be a pixelregion of a display panel.

The timing controller 110 receives various control signals and imagedata, which drive the light emitting unit 140, from the outside (e.g.,from a system for transmitting image data). The timing controller 110realigns the received image data and transmits the realigned image datato the data driver 130. Also, the timing controller 110 generates scancontrol signals and data control signals, which are used to drive therespective scan and data drivers 120 and 130, and transmits thegenerated scan and data control signals to the respective scan and datadrivers 120 and 130.

The scan driver 120 receives a scan control signal supplied from thetiming controller 110 and generates a scan signal corresponding to thescan control signal. The scan signal generated by the scan driver 120 issupplied to unit regions (e.g., pixels or pixel regions) 142 throughscan lines S1 to Sn.

The data driver 130 receives a data control signal and image data, whichare supplied from the timing controller 110, and generates a data signalcorresponding to the data control signal and the image data. The datasignal generated by the data driver 130 is output to data lines D1 toDm. The data signal output to the data lines D1 to Dm is input to pixels142 on a horizontal pixel line, which are selected by the scan signal.

The light emitting unit 140 may include a plurality of pixels 142connected to the scan lines S1 to Sn and the data lines D1 to Dm. Insome embodiments, each of the pixels 142 may include one or more of thebar-type LEDs LD shown in FIG. 1. The pixels 142 selectively emit lightcorresponding to a data signal input from the data lines D1 to Dm when ascan signal is supplied from the scan lines S1 to Sn. As an example,each of the pixels 142 may emit light having a luminance correspondingto the input data signal during each frame period. A pixel 142 suppliedwith a data signal corresponding to a black luminance does not emitlight during the corresponding frame period, thereby providing black.When the light emitting unit 140 is a pixel unit of an active lightemitting display panel, the light emitting unit 140 may be driven bybeing further supplied with first and second pixel power sources as wellas the scan and data signals.

FIGS. 3A-3E are circuit diagrams illustrating a unit region of the lightemitting device according to an embodiment of the present disclosure andillustrate examples of a pixel of a passive light emitting displaypanel. For convenience, a jth (j is a natural number) pixel on an ith (iis a natural number) horizontal pixel line is illustrated in FIGS.3A-3E. As a non-restrictive example related to the pixel shown in FIGS.3A-3E, the pixel may be one of red, green, blue, and white pixels.

Referring to FIG. 3A, the pixel 142 includes a bar-type LED LD connectedbetween a scan line Si and a data line Dj. In some embodiments, a firstelectrode (e.g., an anode electrode) of the bar-type LED LD may beconnected to the scan line Si, and a second electrode (e.g., a cathodeelectrode) of the bar-type LED LD may be connected to the data line Dj.When a voltage equal to or greater than a threshold voltage is appliedbetween the first electrode and the second electrode, the bar-type LEDLD emits light having a luminance corresponding to the magnitude of theapplied voltage. For example, the light emission of the pixel 142 can becontrolled by adjusting the voltage of a scan signal applied to the scanline Si and/or a data signal applied to the data line Dj.

Referring to FIG. 3B, the pixel 142 may include a plurality of bar-typeLEDs LD connected in parallel. In this embodiment, the luminance of thepixel 142 may correspond to the sum of brightnesses of the plurality ofLEDs LD in the pixel 142. When the pixel 142 includes a plurality ofbar-type LEDs LD, including a relatively large number of bar-type LEDsLD, although a defect occurs in some of the bar-type LEDs LD, the defectmay not cause a defect (e.g., may not cause a noticeable defect) of thepixel 142 itself.

Referring to FIG. 3C, the connecting direction of the bar-type LEDs LDprovided in the pixel 142 may be changed. As an example, the firstelectrode (e.g., the anode electrode) of the bar-type LED LD may beconnected to the data line Dj, and the second electrode (e.g., thecathode electrode) of the bar-type LED LD may be connected to the scanline Si. The direction of a voltage applied between the scan line Si andthe data line Dj in the embodiment shown in FIG. 3A and the direction ofa voltage applied between the scan line Si and the data line Dj in theembodiment shown in FIG. 3C may be opposite to each other.

Referring to FIG. 3D, the pixel 142 may also include a plurality ofbar-type LEDs LD connected in parallel.

Referring to FIG. 3E, the pixel 142 may include a plurality of bar-typeLEDs LD connected in different directions. As an example, the pixel 142may include a bar-type LED LD having the first electrode (e.g., theanode electrode) connected to the scan line Si and the second electrode(e.g., the cathode electrode) connected to the data line Dj, and anotherbar-type LED LD having the first electrode (e.g., the anode electrode)connected to the data line Dj and the second electrode (e.g., thecathode electrode) connected to the scan line Si.

The pixel 142 shown in FIG. 3E may be DC driven or AC driven (e.g., maybe driven by an AC current or a DC current). When the pixel 142 shown inFIG. 3E is DC driven, forward connected bar-type LEDs LD may emit lightand reverse connected LEDs LD may not emit light. When the pixel 142shown in FIG. 3E is AC driven, forward connected bar-type LEDs LD mayemit light according to the direction of an applied voltage. Forexample, when the pixel 142 shown in FIG. 3E is AC driven, the bar-typeLEDs LD included in the pixel 142 may alternately emit light accordingto the direction of the applied voltage.

FIGS. 4A-4C are circuit diagrams illustrating a unit region of a lightemitting device according to embodiments of the present disclosure andillustrate examples of a pixel of an active light emitting displaypanel. In FIGS. 4A-4C, components similar or identical to those shown inFIGS. 3A-3E are designated by like reference numerals and detaileddescriptions thereof may be omitted.

Referring to FIG. 4A, the pixel 142 includes a bar-type LED LD and apixel circuit 144 connected thereto.

A first electrode (e.g., an anode electrode) of the bar-type LED LD isconnected to a first pixel power source ELVDD via the pixel circuit 144,and a second electrode (e.g., a cathode electrode) of the bar-type LEDLD is connected to a second pixel power source ELVSS. The first pixelpower source ELVDD and the second pixel power source ELVSS may havepotentials different from each other. As an example, the second pixelpower source ELVSS may have a potential lower by a threshold voltage ormore of the bar-type LED LD than that of the first pixel power sourceELVDD. Each bar-type LED LD emits light having a luminance correspondingto a driving current controlled by the pixel circuit 144.

Although an embodiment in which the pixel 142 includes only one bar-typeLED LD is disclosed in FIG. 4A, the present disclosure is not limitedthereto. For example, the pixel 142 may include a plurality of bar-typeLEDs LD connected in parallel.

In some embodiments, the pixel circuit 144 may include first and secondtransistors M1 and M2 and a storage capacitor Cst. However, thestructure of the pixel circuit 144 is not limited to the embodimentshown in FIG. 4A.

A first electrode of the first transistor (e.g., a switching transistor)M1 is connected to a data line Dj, and a second electrode of the firsttransistor M1 is connected to a first node N1. Here, the first andsecond electrodes of the first transistor M1 are different electrodes.For example, when the first electrode is a source electrode, the secondelectrode is a drain electrode. In addition, a gate electrode of thefirst transistor M1 is connected to a scan line Si. The first transistorM1 is turned on when a scan signal having a voltage (e.g., a low-levelgate-on voltage) at which the first transistor M1 can be turned on issupplied from the scan line Si to allow the data line Dj and the firstnode N1 to be electrically connected to each other. At this time, a datasignal of a corresponding frame is supplied to the data line Dj.Accordingly, the data signal is transferred to the first node N1. Thedata signal transferred to the first node N1 is charged in the storagecapacitor Cst.

A first electrode of the second transistor (e.g., a driving transistor)M2 is connected to the first pixel power source ELVDD, and a secondelectrode of the second transistor M2 is connected to the firstelectrode of the bar-type LED LD. In addition, a gate electrode of thesecond transistor M2 is connected to the first node N1. The secondtransistor M2 controls an amount of driving current supplied to thebar-type LED LD corresponding to a voltage at the first node N1.

One electrode of the storage capacitor Cst is connected to the firstpixel power source ELVDD, and the other electrode of the storagecapacitor Cst is connected to the first node N1. The storage capacitorCst charges a voltage corresponding to the data signal supplied to thefirst node N1 and maintains the charged voltage until a data signal of anext frame is supplied.

For convenience, the pixel circuit 144 having a relatively simplestructure including the first transistor M1 for transferring a datasignal to the inside of the pixel 142, the storage capacitor Cst forstoring the data signal, and the second transistor M2 for supplying adriving current corresponding to the data signal to the bar-type LED LDis illustrated in FIG. 4A. However, the present disclosure is notlimited thereto, and the structure of the pixel circuit 144 may bevariously suitably modified and implemented. As an example, the pixelcircuit 144 may further include other circuit elements, such as atransistor element for compensating for a threshold voltage of thesecond transistor M2, a transistor element for initializing a voltage ofthe first node N1 or a voltage applied to one electrode of the bar-typeLED LD, a transistor element for controlling a light emission period,and/or a boosting capacitor for boosting the voltage at the first nodeN1.

In FIG. 4A, all of the transistors (e.g., both the first and secondtransistors M1 and M2) in the pixel circuit 144 are illustrated asp-type transistors, but the present disclosure is not limited thereto.For example, at least one of the transistors M1 and M2 included in thepixel circuit 144 may be an n-type transistor.

Referring to FIG. 4B, the first and second transistors M1 and M2 may ben-type transistors. The configuration or operation of the pixel circuit144 shown in FIG. 4B is similar to that of the pixel circuit 144 shownin FIG. 4A, except that the connection positions of some of thecomponents are changed due to a change in transistor type. Therefore, amore detailed description of the pixel circuit 144 shown in FIG. 4B willbe omitted.

Referring to FIG. 4C, the pixel 142 may include a plurality of bar-typeLEDs LD connected in different directions. In this embodiment, the pixel142 may be DC driven or AC driven. This has already been described abovewith respect to FIG. 3E, and therefore, a more detailed descriptionthereof will be omitted.

FIG. 5A is a plan view illustrating a unit region of the light emittingdevice according to an embodiment of the present disclosure, and FIG. 5Bis a sectional view taken along the line I-I′ of FIG. 5A.

The unit region illustrated in FIG. 5A may be, for example, anindividual pixel region PXA in which one of the pixels 142 of the lightemitting unit 140 shown in FIG. 2 is provided. For example, the lightemitting device according to an embodiment of the present disclosure maybe a light emitting display device including a plurality of individualpixel regions PXA shown in FIG. 5A, and one of the pixels 142 shown inFIGS. 2-4C may be provided in each pixel region PXA. However, thepresent disclosure is not limited thereto, and the present disclosuremay be applied to other light emitting devices as well as the lightemitting display device.

For convenience, an embodiment in which five bar-type LEDs LD areprovided is illustrated in FIG. 5, but the present disclosure is notlimited thereto. The number and arrangement structure of the bar-typeLEDs LD arranged in the pixel region PXA may be variously suitablymodified.

The luminance of one pixel region PXA may vary depending on the numberof bar-type LEDs LD electrically connected between a first electrode EL1and a second electrode EL2 (e.g., the luminance of the pixel region PXAmay vary based on the number of effective bar-type LEDs LD provided inthe pixel region PXA). When a variation in the number of effectivebar-type LEDs LD greatly varies between the pixel regions PXA, the lightemitting device may exhibit overall non-uniform brightness (or luminous)characteristics.

Thus, in an embodiment of the present disclosure, a metal member MMhaving openings OPN (e.g., cavities, grooves, or cave parts) is providedon the first electrode EU, and one end portion of each bar-type LED LDis in the opening OPN so that the bar-type LEDs LD are more uniformlyarranged (see, e.g., FIG. 5B). According to an embodiment of the presentdisclosure, it is possible to provide a light emitting device and afabricating method thereof in which the number of bar-type LEDs LDarranged in each pixel region PXA is uniform or substantially uniform,thereby achieving more uniform luminance characteristics.

Referring to FIGS. 5A and 5B, the light emitting device according to anembodiment of the present disclosure may include a substrate SUB, afirst electrode EL1, alignment lines AW1 and AW2, a metal member MM, afirst insulating layer INS1, a bar-type LED LD, a connecting member CM,a second insulating layer INS2, and a second electrode EL2.

The substrate SUB may include (or may be made of) an insulativematerial, such as glass or resin. Also, the substrate SUB may include(or may be made of) a flexible material to be bendable or foldable andmay have a single- or multi-layer structure.

For example, the substrate SUB may include at least one of polystyrene,polyvinyl alcohol, poly methyl methacrylate, polyethersulfone,polyacrylate, polyetherimide, polyethylene naphthalate, polyethyleneterephthalate, polyphenylene sulfide, polyarylate, polyimide,polycarbonate, triacetate cellulose, and cellulose acetate propionate.

The substrate SUB may include the transistors of the above-describedpixel circuit. For example, the substrate SUB may be a thin filmtransistor array substrate. In addition, the first electrode EL1 may beelectrically connected to a source/drain electrode of the transistor.

The first electrode EL1 is provided on the substrate SUB. The firstelectrode EL1 may include (or may be made of) a metal. For example, thefirst electrode EL1 may include at least one of a metal, such as gold(Au), silver (Ag), aluminum (Al), molybdenum (Mo), chromium (Cr),titanium (Ti), nickel (Ni), neodymium (Nd), and copper (Cu), or alloysof these metals. The first electrode EL1 may be formed as a singlelayer. However, the present disclosure is not limited thereto, and thefirst electrode EU may be formed as a multi-layer structure in which aplurality of materials from among the metals and the alloys are stacked.

The alignment lines AW1 and AW2 are provided at sides of (e.g., atrespective sides of) the first electrode EL1. The alignment lines AW1and AW2 may be provided in the same layer as the first electrode EL1.The alignment lines AW1 and AW2 may include a first alignment line AW1provided at one side of the first electrode EL1 and a second alignmentline AW2 provided at the other side of the first electrode EL1. Voltageshaving opposite polarities are respectively applied to the firstalignment line AW1 and the second alignment line AW2 so that thebar-type LED LD is deflected in one direction and thereby aligned.

The alignment lines AW1 and AW2 may be formed of the same material asthe metal member MM. The alignment lines AW1 and AW2 may include (or maybe made of) an aluminum-based metal, such as aluminum (Al) or analuminum alloy, a silver-based metal, such as silver (Ag) or a silveralloy, a copper-based metal, such as copper (Cu) or a copper alloy, amolybdenum-based metal, such as molybdenum (Mo) or a molybdenum alloy,chromium (Cr), tantalum (Ta), and/or titanium (Ti).

The metal member MM is provided on the first electrode EL1. The metalmember MM has an opening OPN for accommodating the bar-type LED LD. Themetal member MM may expose the lower first electrode EL1 through theopening OPN.

When the opening OPN is viewed in a cross-sectional view (see, e.g.,FIG. 5B), the opening OPN has a shape in which the width of its insideportion is greater than that of its entrance (or upper portion).Accordingly, the bar-type LED LD can be more stably accommodated in themetal member MM, and separation of the bar-type LED LD may be prevented.

In some embodiments, when viewed on a plane, the opening OPN may have acircular or elliptical shape as shown in FIG. 5A. However, the shape ofthe opening OPN is not limited thereto and may be variously suitablymodified.

In addition, when viewed on a plane, the metal member MM may be formedto cover the first electrode EL1, but the planar size and shape of themetal member MM are not limited.

The thickness of the metal member MM may be less than the length of thebar-type LED LD to ensure a light emission region by exposing a secondend portion LDb of the bar-type LED LD. Therefore, the thickness of themetal member MM and the size of the opening OPN may be determined suchthat a first end portion LDa of the bar-type LED LD extends into theopening OPN and the second end portion LDb is exposed to the outside(e.g., is outside of the opening OPN).

The metal member MM includes (or is formed of) a conductive metalmaterial and may be a metal that facilitates wet etching. The openingOPN in the metal member MM may be formed through an isotropic etchingprocess using a chemical solution. A method of forming the opening OPNwill be further described later.

The material of the metal member MM may include (or may be) analuminum-based metal, such as aluminum (Al) or an aluminum alloy, asilver-based metal, such as silver (Ag) or a silver alloy, acopper-based metal, such as copper (Cu) or a copper alloy, amolybdenum-based metal, such as molybdenum (Mo) or a molybdenum alloy,chromium (Cr), tantalum (Ta), and/or titanium (Ti). When the metalmember MM and the alignment lines AW1 and AW2 are made of the samematerial, the metal member MM and the alignment lines AW1 and AW2 may beconcurrently (or simultaneously) formed.

The first insulating layer INS1 is provided over the metal member MM.For example, the first insulating layer INS covers a front surface(e.g., an upper surface) of the substrate SUB on which the firstelectrode EL1, the alignment lines AW1 and AW2, and the metal member MMare formed. A portion of the first insulating layer INS1 is removed suchthat the opening OPN in the metal member MM is exposed.

The first insulating layer INS1 has an inclined surface SLP which isinclined with respect to the opening OPN (e.g., which is inclined withrespect to the upper surface of the substrate SUB). For example, whenviewed as a cross-section, a region of the first insulating layer INS1that is around the opening OPN may have a funnel shape as shown in FIG.5B. The inclination angle of the inclined surface SLP may be variouslydetermined according to the size of the bar-type LED LD and thestructure (e.g., the size and/or shape) of the opening OPN in the metalmember MM.

The first insulating layer INS1 may be an organic insulating layerincluding (or made of) an organic material. The organic material mayinclude an organic insulating material, such as a polyacryl-basedcompound, a polyimide-based compound, a fluorine-based compound, such asTeflon° (a registered trademark of The Chemours Company of Wilmington,Del.), or a benzocyclobutene-based compound.

The bar-type LED LD is electrically connected to the first electrode EL1at the first end portion LDa of the bar-type LED LD, which is in theopening OPN. The bar-type LED LD is also electrically connected to thesecond electrode EL2 provided at the second end portion LDb of thebar-type LED LD, which protrudes outside of the opening OPN. Thebar-type LED LD may be inserted into the opening OPN using a method ofspraying an LED solution including a plurality of bar-type LED LD ontothe substrate SUB on which the first insulating layer INS is formed. Aportion of the insulating film may be removed before the spraying of theLED solution at where the first end portion LDa of the bar-type LEDs LDare to be accommodated.

The bar-type LED LD extends into the opening OPN and may be aligned tolean obliquely onto the inclined surface SLP of the first insulatinglayer INS1. Here, the aligning direction of the bar-type LED LD may bedetermined by the polarity of a voltage applied to the alignment linesAW1 and AW2. For example, when a voltage having a positive polarity (+)is applied to the first alignment line AW1 and a voltage having anegative polarity (−) is applied to the second alignment line AW2, thefirst end portion LDa of the bar-type LED may face the first alignmentline AW1 and the second end portion LDb of the bar-type LED may face thesecond alignment line AW2. Here, the first end portion LDa of thebar-type LED LD may be an anode electrode, and the second end portionLDb of the bar-type LED LD may be a cathode electrode.

In FIGS. 5A and 5B, an embodiment in which one bar-type LED LD is in oneopening OPN is described as an example. In another embodiment, aplurality of bar-type LEDs LD may be inserted into one opening OPN.

The connecting member CM is provided between the first end portion LDaof the bar-type LED that is in the opening OPN and the first electrodeEL1. The connecting member CM includes (or is formed of) a conductivematerial and increases the electrical contact area between the bar-typeLED LD and the first electrode EL1.

Also, because the connecting member CM is adjacent to the light emissionregion of the bar-type LED LD, the connecting member CM may include (ormay be formed of) a transparent conductive material. For example, theconnecting member CM may include (or may be made of) a transparentconductive material, such as Indium Tin Oxide (ITO), Indium Zinc Oxide(IZO), or Antimony Zinc Oxide (AZO). Light emitted from the bar-type LEDLD (e.g., light emitted from a portion of the bar-type LED LD near thefirst end portion LDa) may be transmitted through the connecting memberCM and reflected by the metal member MM in the opening OPN.

The connecting member CM may be formed using a method of depositing aconductive material on the front surface of the substrate SUB and in theopening OPN and then wet-etching the conductive material such that someof the conductive material remains in the opening OPN. A method offorming the connecting member CM will be further described later.

The second insulating layer INS2 is provided on the first insulatinglayer INS1. The second insulating layer INS2 has a contact opening(e.g., a contact hole) CNT for electrical connection between the secondend portion LDb of the bar-type LED LD and the second electrode EL2. Aportion of the insulating film of the bar-type LED LD may be removedwhile dry etching is being performed to form the contact opening CNT.

The second insulating layer INS2 may be an inorganic insulating layerincluding (or made of) an inorganic material. The organic material mayinclude inorganic insulating materials, such as polysiloxane, siliconnitride, silicon oxide, and silicon oxynitride.

The second electrode EL2 is provided on the second insulating layerINS2. The second electrode EL2 is connected to the second end portionLDb of the bar-type LED LD through the contact opening CNT in the secondinsulating layer INS2. The second electrode EL2 may include (or may bemade of) a metal. For example, the second electrode EL2 may include (ormay be made of) at least one of a metal, such as gold (Au), silver (Ag),aluminum (Al), molybdenum (Mo), chromium (Cr), titanium (Ti), nickel(Ni), neodymium (Nd), and copper (Cu), or alloys of these metals. Whenthe second electrode EL2 includes (or is made of) a metal, the secondelectrode EL2 may be formed very thin or may be formed in a meshstructure to allow light to be transmitted therethrough.

FIGS. 6 and 7 are plan views illustrating pixel regions of lightemitting devices according to other embodiments of the presentdisclosure. Components having the same reference numerals as thosedescribed above may refer to the aforementioned disclosure andoverlapping or repeated descriptions thereof may be omitted.

Referring to FIG. 6, a metal member MM of a light emitting deviceaccording to another embodiment of the present disclosure has an openingOPNa for accommodating a plurality of bar-type LEDs LD1 to LD5. Whenviewed on a plane, the opening OPNa may have a rectangular shape suchthat the bar-type LEDs LD1 to LD5 are inserted and arranged in onedirection.

Referring to FIG. 7, in a light emitting device according to anotherembodiment of the present disclosure, bar-type LEDs LD1 to LD5 may bealigned in a pixel region PXA to be inclined in directions opposite toeach other. When a voltage having a positive polarity (+) is applied toa first alignment line AW1 and a third alignment line AW3 and a voltagehaving a negative polarity (−) is applied to a second alignment lineAW2, first and second bar-type LEDs LD1 and LD2 and third, fourth, andfifth bar-type LEDs LD3, LD4, and LD5 may be aligned in directionsopposite to each other.

As described above, the light emitting uniformity of the light emittingdevice may be improved using an alternating arrangement alignment methodin which bar-type LEDs LD1 to LD5 in one pixel region PXA are aligned indirections different from each other.

FIGS. 8A-8K are sectional views sequentially illustrating a fabricatingmethod of the light emitting device according to an embodiment of thepresent disclosure. Components having the same reference numerals asthose described above may refer to the aforementioned disclosure andoverlapping or repeated description thereof may be omitted.

Referring to FIG. 8A, a first electrode EL1 is formed on a substrateSUB. The first electrode EL1 may be formed by depositing a material ofthe first electrode EL1 on the substrate SUB and then patterning thedeposited material. A photolithography process and an etching processmay be performed to pattern the first electrode EU.

Referring to FIG. 8B, a metal member MM and alignment lines AW1 and AW2are formed on the substrate SUB on which the first electrode EL1 isformed. The metal member MM is formed on the first electrode EL1, and afirst alignment line AW1 and a second alignment line AW2 are formed atopposite sides of the first electrode EL1 (e.g., are formed at one sideand another side of the first electrode EL1, respectively). Thethickness of the metal member MM may be less than the length of abar-type LED LD such that a portion of (e.g., only a portion or lessthan all of) the bar-type LED LD can be accommodated in the metal memberMM.

An embodiment in which the metal member MM and the alignment lines AW1and AW2 are concurrently (or simultaneously) formed of the same materialis illustrated as an example, but the metal member MM and the alignmentlines AW1 and AW2 may be formed of different materials through differentprocesses.

Referring to FIG. 8C, a first insulating layer INS1 is formed over themetal member MM. Here, a portion of the first insulating layer INS1 isremoved such that the metal member MM (e.g., such that a portion of themetal member MM) is exposed therethrough. The first insulating layerINS1 may be an organic insulating layer including (or made of) anorganic material. The organic material may include an organic insulatingmaterial, such as a polyacryl-based compound, a polyimide-basedcompound, a fluorine-based compound, such as Teflon° (a registeredtrademark of The Chemours Company of Wilmington, Del.), or abenzocyclobutene-based compound.

Here, the first insulating layer INS1 may be formed to have an inclinedsurface SLP that is inclined with respect to the metal member MM. Theinclined surface SLP may be formed by depositing a material of the firstinsulating layer INS1 on the substrate SUB and then patterning thedeposited material. A photolithography process and an etching processmay be performed to pattern the inclined surface SLP.

Referring to FIG. 8D, after the first insulating layer INS1 is formed,an opening OPN is formed in the exposed metal member MM. When across-section of the opening OPN is viewed, the opening OPN has a shapein which the width of its inside portion is greater than that of itsentrance. Thus, the bar-type LED LD that is accommodated in the metalmember MM may not be easily separated from the metal member MM.

The opening OPN may be formed through a wet etching process using achemical solution. The wet etching process is an isotropic etchingprocess and may allow the opening OPN to have a shape in which the widthof its inside portion is greater than that of its entrance.

Referring to FIGS. 8E and 8F, bar-type LEDs LD are arranged to beinserted into the opening OPN. For example, an LED solution including aplurality of bar-type LEDs LD is coated on the first insulating layerINS1. After the LED solution is coated or at the same or substantiallythe same time as when the LED solution is coated, an electric field isformed by applying a voltage to the alignment lines AW1 and AW2 toinduce self-alignment of the randomly distributed bar-type LEDs LD.

In addition, as shown in FIG. 8E, bar-type LEDs LD may be inserted intothe opening OPN using a method of cleaning the substrate having the LEDsolution provided thereon in one direction using a cleaning solution WT.Here, some of the plurality of bar-type LEDs LD in the LED solution areinserted into the opening OPN and the others of the plurality ofbar-type LEDs LD may be removed through the cleaning process.

In another embodiment, the bar-type LEDs LD may be inserted into theopening OPN by independently spraying the LED solution or spraying theLED solution together with the cleaning solution WT.

Therefore, as shown in FIG. 8F, the bar-type LED may be aligned to leanobliquely onto the inclined surface SLP of the first insulating layerINS1. In addition, the bar-type LED LD is electrically connected to thefirst electrode EL1 when the first end portion LDa of the bar-type LEDLD is in the opening OPN.

Referring to FIGS. 8G and 8H, a connecting member CM, which is providedbetween the first end portion LDa of the bar-type LED LD in the openingOPN, and the first electrode EL1 may be formed. The connecting member CMincludes (or is formed of) a conductive material and increases theelectrical contact area between the bar-type LED LD and the firstelectrode EL1. In some embodiments, the connecting member CM may include(or may be made of) a transparent conductive material, such as IndiumTin Oxide (ITO), Indium Zinc Oxide (IZO) or Antimony Zinc Oxide (AZO).

A connecting member layer CML is formed on the first insulating layerINS1. For example, the connecting member layer CML may be deposited onthe front surface of the substrate SUB to be filled in the opening OPN.Then, the connecting member layer CML is etched such that a portion ofthe connecting member layer CML remains in the opening OPN. For example,a portion of the connecting member layer CML in the opening OPN, whichoverlaps the bar-type LED LD, may remain (e.g., may not be etched). Awet etching process may be used as the etching process of the connectingmember layer CML.

Referring to FIGS. 8I and 8J, a second insulating layer INS2 is formedon the first insulating layer INS1. The second insulating layer INS2 maybe an inorganic insulating layer including (or made of) an inorganicmaterial. The organic material may include inorganic insulatingmaterials, such as polysiloxane, silicon nitride, silicon oxide, andsilicon oxynitride.

A material of the second insulating layer INS2 is deposited on the firstinsulating layer INS1. Then, a contact opening CNT is patterned at aposition corresponding to the bar-type LED LD. A portion of theinsulating film of the bar-type LED LD may be removed while dry etchingis being performed to form the contact opening CNT.

Referring to FIG. 8K, a second electrode EL2 is formed on the secondinsulating layer INS2. The second electrode EL2 is electricallyconnected to a second end portion LDb of the bar-type LED LD through thecontact opening CNT, which passes through the second insulating layerINS2.

The second electrode EL2 may include (or may be made of) a metal. Forexample, the second electrode EL2 may include (or may be made of) atleast one of a metal, such as gold (Au), silver (Ag), aluminum (Al),molybdenum (Mo), chromium (Cr), titanium (Ti), nickel (Ni), neodymium(Nd), and copper (Cu), or alloys of these metals. Also, the secondelectrode EL2 may be formed as a single layer. However, the presentdisclosure is not limited thereto, and the second electrode EL2 may beformed as a multi-layer structure in which a plurality of materials fromamong the metals and the alloys are stacked.

As described above, according to embodiments of the present disclosure,the metal member MM having the opening OPN is provided on the firstelectrode EL1, and one end portion of the bar-type LED LD is insertedinto the opening OPN so that bar-type LEDs LD can be more uniformlyarranged. Accordingly, the light emitting uniformity of the lightemitting device is improved.

Example embodiments of the present disclosure have been disclosedherein, and although specific terms are employed, they are used and areto be interpreted in a generic and descriptive sense only and not forpurpose of limitation. In some instances, as would be apparent to one ofordinary skill in the art as of the effective filing date of the presentapplication, features, characteristics, and/or elements described inconnection with a particular embodiment may be used singly or incombination with features, characteristics, and/or elements described inconnection with other embodiments unless otherwise specificallyindicated. Accordingly, it will be understood by those of skill in theart that various changes in form and details may be made to thedescribed example embodiments without departing from the spirit andscope of the present disclosure as set forth in the following claims andtheir equivalents.

What is claimed is:
 1. A light emitting device comprising: a substrate;a first electrode on the substrate; a metal member on the firstelectrode, the metal member having a cavity; a first insulating layer onthe metal member, the first insulating layer exposing the cavitytherethrough; a bar-type LED having a first end portion and a second endportion, the first end portion being electrically connected to the firstelectrode in the cavity, the second end portion protruding outside ofthe cavity; and a second electrode on the first insulating layer, thesecond electrode being connected to the second end portion of thebar-type LED.
 2. The light emitting device of claim 1, wherein a widthof an inside portion of the cavity is greater than a width of anentrance to the cavity.
 3. The light emitting device of claim 1, whereina thickness of the metal member is less than a length of the bar-typeLED.
 4. The light emitting device of claim 1, wherein the cavity in themetal member exposes the first electrode.
 5. The light emitting deviceof claim 1, further comprising a plurality of bar-type LEDs in thecavity.
 6. The light emitting device of claim 1, wherein the firstinsulating layer has an inclined surface inclined with respect to thecavity, and wherein the bar-type LED leans obliquely onto the inclinedsurface of the first insulating layer.
 7. The light emitting device ofclaim 6, wherein one pixel region comprises a plurality of bar-typeLEDs, and wherein the bar-type LEDs in the one pixel region are inclinedin the same direction.
 8. The light emitting device of claim 6, whereinone pixel region comprises a plurality of bar-type LEDs, and wherein thebar-type LEDs in the one pixel region are inclined in directionsdifferent from each other.
 9. The light emitting device of claim 1,further comprising a connecting member between the first end portion ofthe bar-type LED in the cavity and the first electrode.
 10. The lightemitting device of claim 1, further comprising a second insulating layerbetween the first insulating layer and the second electrode, wherein thesecond insulating layer has a contact opening at where the second endportion of the bar-type LED and the second electrode are electricallyconnected to each other.
 11. The light emitting device of claim 1,further comprising alignment lines at both sides of the first electrode.12. A method of fabricating a light emitting device, the methodcomprising: forming a first electrode on a substrate; forming a metalmember on the first electrode; forming a first insulating layer over themetal member, removing a portion of the first insulating layer to exposethe metal member; forming a cavity in the metal member; arranging abar-type LED such that a first end portion of the bar-type LED is in thecavity and electrically connected to the first electrode; and forming asecond electrode on the first insulating layer, the second electrodebeing electrically connected to a second end portion of the bar-typeLED.
 13. The method of claim 12, wherein the cavity in the metal memberhas a shape in which a width of its inside portion is larger than awidth of its entrance.
 14. The method of claim 13, wherein the cavity isformed by isotropic etching.
 15. The method of claim 12, wherein athickness of the metal member is less than a length of the bar-type LED.16. The method of claim 12, wherein the first insulating layer has aninclined surface inclined with respect to the cavity, and wherein thebar-type LED leans obliquely onto the inclined surface of the firstinsulating layer.
 17. The method of claim 12, wherein the arranging ofthe bar-type LED comprises: providing an LED solution comprising aplurality of bar-type LEDs on the first insulating layer; and after theproviding the LED solution, cleaning the substrate in one direction. 18.The method of claim 12, further comprising forming a connecting memberbetween the first end portion of the bar-type LED that is in the cavityand the first electrode.
 19. The method of claim 18, wherein the formingof the connecting member comprises: forming a connecting member layer onthe first insulating layer and in the cavity; and etching the connectingmember layer such that a portion of the connecting member layer remainsin the cavity.
 20. The method of claim 12, further comprising forming asecond insulating layer having a contact opening on the first insulatinglayer, the second end portion of the bar-type LED and the secondelectrode being electrically connected to each other at the contactopening.